Back extension — Muscles Worked & RPE Load Guide
Back extension targets Hamstrings, Glutes as primary movers (1.0× set credit) alongside Lower Back (0.5× synergist credit). Cam-matched resistance across sticking points.
17-Muscle Fractional Recruitment & Weekly MEV–MRV Landmarks
Each working set ≥ RPE 6 triggers fractional hard-set credit toward Renaissance Periodization / Schoenfeld weekly hypertrophy landmarks.
| Muscle Group | Mechanical Role | Effort Share | Weekly Optimal Band (MEV–MAV) | Frequency & Research |
|---|---|---|---|---|
| Hamstrings | Primary (1.0× set) | 45% | 4–16 sets/wk (MRV 20) | 2–4x / week · Evidence |
| Glutes (Gluteus Maximus / Medius) | Primary (1.0× set) | 35% | 4–16 sets/wk (MRV 20) | 2–4x / week · Evidence |
| Lower Back (Spinal Erectors) | Secondary (0.5× set) | 20% | 4–10 sets/wk (MRV 14) | 1–3x / week · Evidence |
Back extension Worked Wathan RPE Prescription Table (kg)
Worked kg values computed for Back extension using a worked 180.0 kg reference 1RM (Machine) rounded to 5 kg machine increments. Mechanics: Externally braced cam track; resistance curve: Cam-matched resistance across sticking points.
| Reps | RPE 9.5 | RPE 9 | RPE 8.5 | RPE 8 | RPE 7 |
|---|---|---|---|---|---|
| 3 reps | 0 kg (89%) | 0 kg (86%) | 0 kg (86%) | 0 kg (83%) | 0 kg (81%) |
| 5 reps | 0 kg (83%) | 0 kg (81%) | 0 kg (81%) | 0 kg (81%) | 0 kg (78%) |
| 8 reps | 0 kg (75%) | 0 kg (75%) | 0 kg (75%) | 0 kg (72%) | 0 kg (72%) |
| 10 reps | 0 kg (72%) | 0 kg (72%) | 0 kg (69%) | 0 kg (69%) | 0 kg (67%) |
| 12 reps | 0 kg (69%) | 0 kg (67%) | 0 kg (67%) | 0 kg (67%) | 0 kg (64%) |
Strong, Hevy & French/English CSV Import Labels
STRUGGL automatically maps these exact workout-tracker strings to canonical Back extension volume and e1RM records on zero-login Wrapped CSV upload.
Taken-Rack Substitutes & Biomechanical Swaps
Ranked deterministically by weighted primary-muscle overlap inside the same measurement family.
Verified Peer-Reviewed Literature (PubMed & DOI)
| Peer-Reviewed Paper | Author & Journal | External Reference |
|---|---|---|
| Influence of joint position on electromyographic and torque generation during maximal voluntary isometric contractions of the hamstrings and gluteus maximus muscles. | Worrell (2001) · The Journal of orthopaedic and sports physical therapy | PubMed 11767248 ↗ |
| Progressive overload without progressing load? The effects of load or repetition progression on muscular adaptations. | Plotkin (2022) · PeerJ | PubMed 36199287 ↗ |
| Muscle metabolism during intense, heavy-resistance exercise. | Tesch (1986) · European journal of applied physiology and occupational physiology | PubMed 3758035 ↗ |